The major goal of the proposed research is the analysis of the process of reverse transcription by RLV DNA polymerase, through continuing biochemical investigation both in vitro and in vivo. Emphasis will be placed on the process of DNA synthesis directed by virion genomic 70S RNA, and the possible role(s) of viral and cellular proteins in maximizing the efficiency of that synthesis. The enzymological studies to be carried out will explore the mechanism of stimulation of the process of reverse transcription by polyamines and related compounds which have been shown to interact with nucleic acids, and to determine the mechanism by which the presence of purified, native virion structural proteins such as p10 and pp12 stimulate the process of reverse transcription. We also intend to fully characterize the high molecular weight intracytoplasmic form of RLV DNA polymerase, and to determine whether or not it is present in an in vivo MuLV-synthesizing system such as the AKR mouse thymus gland.